Learn Hardcore Ukrainian: Я читаю книгу під час дощу.

Під час translates to "during" in English. In Ukrainian, this preposition requires that the following noun be in the genitive case. That’s why дощ becomes дощу, indicating the time during which the action is taking place.

How is the present continuous idea conveyed in Я читаю книгу, given that Ukrainian does not have a separate continuous tense?

Ukrainian uses the simple present form, читаю, to express both habitual and ongoing actions. Unlike English, which distinguishes between "I read" and "I am reading," Ukrainian relies on context to convey whether the action is in progress.

Why is the noun книга changed to книгу in this sentence?

In this sentence, книгу serves as the direct object of the verb читаю. Ukrainian marks direct objects using the accusative case, and for feminine nouns like книга, the accusative form is книгу.

What function does the pronoun Я serve, and how does it compare to its use in English?

The pronoun Я is the subject of the sentence, equivalent to "I" in English. It clearly identifies who is performing the action, and its use is similar to English where the subject must be explicitly stated.